"As for why?" he added in another tweet. "Because I forgot to reply to an email."

When I followed up with Allegra in a phone call, he explained that the email he forgot to answer was an offer to continue his employment at Apple as a remote intern. At Apple, apparently, offer letters are taken rather seriously, and Allegra soon learned that his had been rescinded. "I wasn’t too happy about it, but it didn’t seem like I was able to fix it," he says. "So that’s what it is."

Allegra added that his departure from Apple was more complicated than just a forgotten email, and that "it wasn't a bad ending," but declined to say more. He also wouldn't say what he worked on during his two internships at Apple--one in the fall of last year and one over the past summer--but he said he enjoyed his time in Cupertino.

Under the handle Comex, Allegra rose to hacker fame building "jailbreaking" tools for iPhones and iPads like Jailbreakme 2 and Jailbreakme 3, which allowed users to remove the restrictions on iOS devices that limit them to downloads only from Apple's official app store. Both tools entirely defeated iOS's strict security measures--perhaps the strongest of any consumer operating system--when users simply visited a website, grabbing the attention of the security community and attracting millions of visitors eager to liberate their phones.

Allegra decided to switch sides in the Apple hacking game last summer and accept Apple's employment offer, he says, because he was on leave from Brown, and because he was "bored" of jailbreaking. "To clear the record a bit: anyone who thinks I 'sold out 'for money doesn’t know what he’s talking about," Allegra added on Twitter.

When I asked Allegra what he plans to work on now, he said he'll focus on his studies at Brown, and doesn't foresee working on new jailbreaking tools for iOS any time soon. That may come as a disappointment for iPhone users, who have been waiting for a crack for iOS 6, a feat that may be far more difficult for the jailbreaking community to pull off than for earlier mobile operating systems due to Apple's further tightening of iOS's security measures.

Allegra said his employment contract with Apple may in fact complicate his future work on reverse engineering the company's products. "I don’t know whether or not it’s against the terms, but it probably is," he says.

But Comex may not be out of the jailbreaking scene altogether. Just after his note on Twitter about leaving Apple, Allegra referenced another possible target. "So..." he wrote. "I hear the Wii U is coming out in a month."